In the experiments proposed for the coming year we will continue to study the effects of bile acids on intestinal transit time. These studies will be performed in healthy volunteers with a jejunal perfusion technique which uses dilution curves for transit time determination. A separate set of experiments will study the effects of changes of water movement on solute absorption in the presence of dihydroxy bile acids and fatty acids in the human jejunum. In particular, we want to study whether fluid secretion induced by an osmotic load superimposed on the secretory effect of fatty acids will further reduce solute absorption, and whether a reduction of fluid secretion by glucose will enhance absorption of dihydroxy bile acids. Further experiments are planned to evaluate the interaction between cholesterol and fatty acids to define the mechanism by which cholesterol inhibits fatty acid induced fluid secretion.